A number of medical conditions may be treated using ablative techniques or devices to induce cellular apoptosis. Ablative techniques, generally, result in the killing of abnormal tissue at an area of interest. Killing the abnormal tissue may result in an efficacious treatment for a medical condition. For example, atrial fibrillation may be the result of abnormal electrical activity in the left atrium and the pulmonary vein, and may be treatable by ablation of the abnormal tissue within the left atrium and/or the pulmonary vein.
Atrial fibrillation is a serious medical condition that is the result of abnormal electrical activity within the heart. This abnormal activity may occur at regions of the heart including the sino-atrial (SA) node, the atriovenricular (AV) node, the bundle of His, or within other areas of cardiac tissue. Moreover, atrial fibrillation may be caused by abnormal activity within an isolated focal center within the heart. It is believed that these foci can originate within the pulmonary vein, particularly the superior pulmonary veins.
Minimally invasive techniques have been described that use ablation catheters to target the pulmonary vein with the hope of ablating foci having abnormal electrical activity. The techniques typically are characterized by application of energy to cause lesions within the foci or other areas possessing abnormal electrical activity. Some ablation devices utilize radio frequency (RF) energy for ablation, including the device disclosed in U.S. Pat. No. 6,024,740 to Lesh et al. The RF energy devices may be used to ablate an area of interest with heat.